A scroll compressor is used to compress air or another gas through the interaction of two spiral-shaped windings that are each affixed on a plate, whereby these windings mesh together and are moved eccentrically with respect to one another to enclose air chambers that continuously become smaller due to the aforementioned movement and which thereby move from an inlet to an outlet, whereby the pressure of the air in these air chambers increases due to the compression in the increasingly smaller air chambers.
Generally one of the two scrolls is a fixed scroll that forms part of a stator and the other scroll forms part of a rotor with a shaft driven by a motor, and on which the rotor is affixed eccentrically.
Such a type of compressor is known from EP 2.224.136, for example.
When compressing the air, heat is inevitably generated that is carried away to the environment via external cooling fins on the stator and the rotor.
Generally active cooling is applied by means of a fan that draws in air or another coolant gas and blows this coolant gas along and over the cooling fins.
For the rest of the description and the claims it will be assumed that the coolant gas is air, although the invention is not limited to an air-cooled scroll compressor.
In practice the fan and the compressor are driven by a common drive.
Conventionally a radial fan is used with a rotor that is affixed in a housing, whereby surrounding air is drawn in through an axial inlet in the axial direction of the fan, in other words is drawn in in the axial direction of the rotor, and is channelled to the other side of the drive by the housing in order to be blown out over and along the cooling fins of the scroll compressor via a deflector.
Housings of this type are formed by, on the one hand, a volute for the housing of the rotor of the fan with an axial inlet for drawing in air in the axial direction parallel to a geometric axis through the center of the inlet and perpendicular to the plane of the inlet and a radial outlet, and, on the other hand, an outlet bend fitting to this radial outlet with an axial output, whereby the volute is formed by two opposite walls, at least one of which is provided with a passage that forms the aforementioned inlet, and which are connected together by a transverse wall whose radial distance to the aforementioned axis gradually increases in a rotation direction around the axis from a starting point to an end point, and whereby on the inside of the housing the outlet bend connects to the transverse wall with an included angle at the location of the aforementioned starting point.
A disadvantage of known housings is that they involve relatively large flow losses, which results in a reduced coolant flow of the air drawn in and thus a less efficient compression and a lower general compressor performance, or even in the unusability of the compressors at higher ambient temperatures of more than 40 to 50° C., for example.